Vanillin is the major principle flavor ingredient in vanilla extract and is also noted as a nutraceutical because of its anti-oxidant and antimicrobial properties. Vanillin can be used as a masking agent for undesirable flavors of other nutraceuticals. Vanilla extract is obtained from cured vanilla beans, the bean-like pod produced by Vanilla planifolia, a tropical climbing orchid.
Vanilla extract is widely used as a flavor by the food and beverage industry, and is used increasingly in perfumes. The U.S. annual consumption of vanilla beans, all of which are imported from foreign countries, is 1,200–1,400 tons, with a market value of about $100 million. By FDA definition, vanillin can be labeled as natural only when it is derived from vanilla beans. Currently, natural vanilla obtained through extraction of vanilla beans as described below, costs between $1,500 and $3,000 per kilogram. Vanillin is also produced by molecular breakage of curcumin, eugenol or piperin at a cost of $1,000/kg or less. However, vanillin produced by this method can be labeled as a natural flavor only in non-vanilla flavors. Vanillin chemically synthesized from guaiacol is consumed at a rate of about 800 tons per year in the United States for the food and beverage industry, at a cost of production of about $15/kg.
Natural vanilla extract currently produced from vanilla beans is presently the most desirable form of vanilla, due to the recent demand for natural food ingredients. The areas of the world capable of supporting vanilla cultivation are limited, due to its requirement for a warm, moist and tropical climate with frequent, but not excessive rain, and moderate sunlight. The primary growing region for vanilla is around the Indian Ocean, in Madagascar, Comoros, Reunion and Indonesia.
The production of vanilla beans is a lengthy process that is highly dependent on suitable soil and weather conditions. Beans (pod-like fruit) are produced after 4–5 years of cultivation. Flowers must be hand-pollinated, and fruit production takes about 8–10 months. The characteristic flavor and aroma develops in the fruit after a process called “curing,” lasting an additional 3–6 months. For a complete review of the vanilla growing and curing process, see D. Havkin Frenkel & R. Dorn, “Vanilla,” Chapter 4 in Spices: Flavor Chemistry and Antioxidant Properties, (Eds. Risch & Ho), American Chemical Society, Washington, 1997.
Interest has focused recently on plant cell and tissue culture as an approach to control quality and yield of vanilla production and to solve some of the agronomic problems associated with growing vanilla. Plant tissue culture should be useful for three objectives: (1) micropropagation of vanilla plants; (2) production of vanillin and other secondary products associated with vanilla flavor; and (3) improving production of vanillin in culture or in intact plants by elucidating and manipulating the biosynthetic pathways of vanillin and other flavor compounds. In connection with this last objective, efforts have been made to commercialize production of vanillin, the most valuable component of vanilla, by using plant cell culture. However, these efforts have not resulted in economically significant amounts of vanillin production, perhaps due in part to the heretofore incomplete understanding of the vanillin biosynthetic pathway.
From the foregoing, it can be seen that improvement of vanillin production, either in tissue culture or in intact plants, would be of significant agronomic and economic advantage. Accordingly, it is an object of this invention to provide means for obtaining high yields of vanillin from cultured cells and tissues. It is another object of this invention to improve vanillin production in intact vanilla plants.